FLOW ANALYSIS OF FLUID IN DOUBLE POROUS MEDIA INCLUDING THE EFFECTS OF THE QUADRATIC-GRADIENT TERM

Traditional well-test models for liquid flow are not consistent with material balance equation. According to assumption of slightly compressible fluid, the quadratic gradient term in nonlinear partial differential equation is usually neglected. This method is questionable for live oil and low permeability reservoirs. It is known that the neglect of the quadratic gradient term results in errors for large values of well-test time. A method that is consistent with material balance equation for fractured reservoir with double porosity is proposed in this paper. All terms in nonlinear partial differential equation are retained. Double porosity models are built. The numerical solutions of double porosity models are obtained by Douglas-Jones predictor-corrector method in a constant rate production and constant-pressure production in an infinitely large system. This paper addresses the change rule of pressure when fluid compressibility and double porosity parameters change. The plots of typical pressure curves are given, and the results can be applied to well-test analysis.